1. Field of the Invention
The present invention generally relates to a new and improved spreader bar for use in lifting operations.
2. Description of the Related Art
Spreader bars are commonly used in industry for lifting large objects with a single hook that is attached to the lift cables of a helicopter, crane or other lifting device. A lifting hook is commonly provided with a pair of slings that depend from the helicopter or crane hook at angles in a bridle fashion. Each of the slings contacts a respective end portion of the spreader bar and then continues downwardly wherein it is attached to a load that is to be lifted.
One particular problem with spreader bars relates to the size of the spreader bar relative to the particular load that is to be lifted. Some prior art spreader bars have telescoping sections to adjust the spreader bar to different lengths to accommodate different loads. Such telescoping spreader bars have operated well in lifting relatively light loads of a few thousand pounds but have exhibited problems in lifting very heavy loads. Another problem of prior art spreader bars is related to transportation and storage of the spreader bar. Many prior art spreader bars are extremely heavy when compared to the strength of an average worker. Therefore, it is difficult for a single worker to move, lift and transport many of the prior art spreader bars.
The prior art reveals several different spreader bar apparatuses and similar devices. U.S. Pat. Nos. 6,079,760 and 6,296,288 disclose a spreader bar that comprises a plurality of bar sections that are connected end-to-end to form a lifting bar with a central longitudinal axis and with left and right end bar end members. U.S. Pat. No. 6,412,649 discloses a spreader bar that includes an elongated bar member that has end portions which support a flexible lifting member. U.S. Pat. No. 5,863,085 discloses a spreader bar that has a rigid elongated support bar. End caps are connected to the rigid elongated support bar in order to use the spreader bar in a lifting operation. The end caps have sockets that fit over the ends of the bar. U.S. Pat. No. 5,716,088 discloses a lifting frame and a single-piece spreader bar. The end caps have sockets that fit over the ends of the bar. U.S. Pat. No. 5,603,544 discloses compression cap assemblies that are used with the ends of a spreader bar. U.S. Pat. No. 4,842,314 discloses a pipe lift cap assembly comprising a pair of first and second cap members that can be removably attached to respective ends of a pipe or casing. The end caps have sockets that fit over the ends of the bar. U.S. Pat. No. 4,538,849 discloses a spreader bar assembly that has a pair of separate elongated spreader bars. Each spreader bar is supported independently by alternate radially branching lines. U.S. Pat. No. 4,397,493 discloses a spreader bar assembly that utilizes a single rigid member. U.S. Pat. No. 3,829,145 discloses a spreader bar extension that comprises a rectangular upper framework. U.S. Pat. No. 2,020,174 discloses a vehicle hoist frame that comprises two tubular rods that are interconnected at the center by a pivot. Each tubular rod has a plate-disc at the center of the tubular rod. Each disc has a slot in the shape of the arc of a circle.
What is needed is a new and improved spreader bar apparatus that has the required strength for military and commercial applications, but which is compact, light-weight and relatively inexpensive to manufacture.